The Demon Soul
by Samantha C. Winchester
Summary: *One-shot that may progress as a story* The Mark of Cain has taken hold of Dean, and he's a full-blown demon. Sam has no idea Dean hasn't come back from the dead as a human, but Cas can tell as soon as he walks through the door. How will Team Free Will get past this one? (My first fic, Destiel is definitely present. Tell me what you think! Should I continue?)


Dean was alive. Or, Dean's _body_ was. But he wasn't Dean anymore. Cas knew. Sam didn't have a clue. Sam just thought Crowley brought Dean back out of the kindness of his heart, or... Whatever the King of Hell kept his kindness in. Or maybe Crowley thought the boys wouldn't go after him if he played the hero for once, and he was right, after this Sam had no intention to kill him. Yeah, Dean was a bit different, but Sam was just happy his big brother was up and walking again, and he didn't even have to sell his soul for it.

Once Dean walked out of his bedroom, alive, Sam hugged him, and made sure to pray to Cas and tell him Dean was okay, everyone was okay, and that he should get his feathery ass down there. Cas got to the bunker as quickly as he could, but as soon as he walked through the door he knew.

Dean wasn't Dean.

Sam was still Sam, his soul still shining brightly, with a few tarnishes here and there, but that's to be expected from The Boy With Demon Blood.

But Dean, the Dean whose soul always shined the brightest in the room, the Dean whose soul was so pure the minute he died he'd be sent straight to heaven, the Dean whose heart and soul Cas loved so much, wasn't in the room. Dean's soul wasn't Dean's anymore. It was black, and ugly, it was twisted, it was _demon. _

Cas staggered back a bit, feeling his heart drop. He'd almost rather Dean be dead, at least he'd be up in heaven with damn near everyone he loved.

Sam noticed Cas stumble and rushed to his side. "Cas, are you okay? Is it your grace, is it failing?"

Castiel knew better than to say anything to Sam about Dean, at least for right now, so he replied, "No, uh, it was just a... long trip, and I'm just so surprised and... pleased to see Dean's okay. Could I, um, speak to him alone for a minute?"

Sam glanced at the both of them, shrugged, and left the room. He learned by now that if Cas and Dean wanted to talk, it's best to not be around. At least he won't feel like such a third wheel that way.

As soon as Sam left the room and shut the door, The Thing That Wasn't Dean said, "Look, Cas, this isn't what you think, I..."

But before it could finish its sentence Cas had it pinned up against the wall. "You're not Dean," he growled. "So what the hell are you?"

"Cas it's still me! I can explain."

"It's Castiel to you. Now you son of a bitch better tell me what's happened to Dean because I know he's not in heaven. Have you possessed him?"

"No, Cas! Please. It's me. It was The Mark, apparently when you sign up to get it tatted on you, there's fine print saying that once you die, you come back as this, as a... demon. But it's still me, it's still _mostly_ me. Please, don't tell Sammy. I don't think he could deal with it. Crowley, he's tried to teach me how to keep the black eyes under control. Sam wouldn't have to know."

Cas faintly recalled a story about Cain taking his own life and The Mark bringing him back as a demon, and had no choice but to let "Dean" go.

"Damn it, Dean! I told you, The Mark of Cain isn't to be taken lightly. If you hadn't gotten yourself into this mess, you'd still be you. Instead you've turned into the monster you've been hunting all your life."

Cas knew those words probably struck a chord with Dean, they _were_ harsh. But, maybe they didn't, because it's not _truly_ Dean, is it? Either way, Cas didn't care. He should hear how stupid he was, how much he screwed up. He should have let Crowley find some other lackey to kill Abbadon, it didn't have to be him. The risks were too great, there were too many people who cared about him, who loved him, and he should have known that. But, this is a Winchester. They do stupid things all the time in the name of the Greater Good, even if that stupid thing has terrible repercussions, whether it be for the world or just for them.

More specifically, this is Dean Winchester. The man who sold his soul to bring his brother back to life because he loved him too much and couldn't bear to live without him. The man who suffered in hell for 40 years just so that brother could keep living and breathing. The man who saved countless lives, the man who almost single-handedly stopped the apocalypse, the man who jumped at the chance to risk his life for someone, anyone, because he thought their lives were worth more than his, the man who thought he wasn't worth anything.

The man who Cas pulled from hell. The man who Cas willingly fell from heaven for. The man Cas died for, multiple times. The man Cas needed to redeem himself to every time he screwed up trying to save heaven. The man who'd "rather have him, cursed or not." The man who was determined to save Cas from purgatory. The man who "did not leave" him. The man Cas could not kill. The man who Cas did everything for. The man Cas fell in love with.

Knowing all of this, Cas realized maybe Dean was still in there somewhere. Maybe he was still inside that dark, twisted soul, crying for help. Dying to get out. Maybe some parts of Dean still shined through. He does still care about Sam, after all.

Cas sighed and said, "There's got to be a way to fix this. There's an answer to everything _somewhere. _Maybe we can reverse it, make you you again. I'll start looking for answers, maybe send my most trusted brothers and sisters out looking as well. I won't tell Sam..."

Dean sighed with relief. "Cas, thank you, I owe you..."

"For _now. _We could use his help, and he'll probably find out soon enough, he's smart. I'll give it a month. If he doesn't know by then, I'm telling him." Dean's smile faltered, but he nodded.

Cas turned towards the door, shaking his head. "I'll tell Sam something's come up in heaven and that I can't stay. I'll start looking for answers right away. In the meantime, just... lay low for a while."

As Cas left the room, he mumbled under his breath, "Damn it, Dean, the things I do for you."


End file.
